#!/bin/sh
# Detects container limits
# If found these are exposed as the following environment variables:
#
# - CONTAINER_MAX_MEMORY
# - CONTAINER_CORE_LIMIT
#
# This script is meant to be sourced.

if [ "${SCRIPT_DEBUG}" = "true" ] ; then
    set -x
fi

# query the resources based on cgroups version
# cgroups v1 points to tmpfs
# cgroups v2 points to cgroup2fs
CGROUPS_VERSION="v1"
tmp_fs=$(stat -fc %T /sys/fs/cgroup)
if [ "${tmp_fs}" = "cgroup2fs" ]; then
    CGROUPS_VERSION="v2"
fi


ceiling() {
    awk -vnumber="$1" -vdiv="$2" '
        function ceiling(x){
            return x%1 ? int(x)+1 : x
        }
        BEGIN{
            print ceiling(number/div)
        }
    '
}

# Based on the cgroups limits, figure out the max number of core we should use
core_limit() {
    if [ "${CGROUPS_VERSION}" = "v1" ]; then
        local cpu_period_file="/sys/fs/cgroup/cpu/cpu.cfs_period_us"
        local cpu_quota_file="/sys/fs/cgroup/cpu/cpu.cfs_quota_us"
        if [ -r "${cpu_period_file}" ]; then
            local cpu_period="$(cat ${cpu_period_file})"
            if [ -r "${cpu_quota_file}" ]; then
                local cpu_quota="$(cat ${cpu_quota_file})"
                # cfs_quota_us == -1 --> no restrictions
                if [ "x$cpu_quota" != "x-1" ]; then
                    ceiling "$cpu_quota" "$cpu_period"
                fi
            fi
        fi
    else
        # v2
        # on cgroupsv2 the period and quota a queried from the same file
        local cpu_max_file="/sys/fs/cgroup/cpu.max"
        # when both are set we will have the following output:
        # $MAX $PERIOD
        # where the first number is the quota/max and the second is the period
        # if the quota/max is not set then we will have only the period set:
        # max 100000
        if [ -r "${cpu_max_file}" ]; then
            local cpu_max="$(cat ${cpu_max_file})"
            if [ "x$cpu_max" != "x" ]; then
                local cpu_quota="$(echo $cpu_max | awk '{print $1}')"
                local cpu_period="$(echo $cpu_max | awk '{print $2}')"
                if [ "$cpu_quota" != "max" ] && [ "x$cpu_period" != "x" ]; then
                    ceiling "$cpu_quota" "$cpu_period"
                fi
            fi
        fi
    fi
}

max_unbounded() {
    cat /proc/meminfo | grep 'MemTotal:' | awk '{print $2*1024}'
}

container_memory() {
    local max_mem_unbounded="$(max_unbounded)"
    # High number which is the max limit unit which memory is supposed to be unbounded.
    if [ "${CGROUPS_VERSION}" = "v1" ]; then
        local mem_file="/sys/fs/cgroup/memory/memory.limit_in_bytes"
        if [ -r "${mem_file}" ]; then
            local max_mem="$(cat ${mem_file})"
            if [ ${max_mem} -lt ${max_mem_unbounded} ]; then
                echo "${max_mem}"
            fi
        fi
    else
        # v2
        local mem_file="/sys/fs/cgroup/memory.max"
        if [ -r "${mem_file}" ]; then
            local max_mem="$(cat ${mem_file})"
            # if not set, it will contain only the string "max"
            if [ "$max_mem" != "max" ]; then
                if [ ${max_mem} -lt ${max_mem_unbounded} ]; then
                    echo "${max_mem}"
                fi
            fi
        fi
    fi
}

min() {
    printf "%s\n" "$@" | sort -g | head -n1
}

local limit="$(core_limit)"
if [ x$limit != x ]; then
    export CONTAINER_CORE_LIMIT="$limit"
fi

local env_core_limit="$(min $CONTAINER_CORE_LIMIT $JAVA_CORE_LIMIT)"
if [ -n "$env_core_limit" ]; then
    export CORE_LIMIT="$env_core_limit"
fi

local max_mem="$(container_memory)"
if [ x$max_mem != x ]; then
    export CONTAINER_MAX_MEMORY="$max_mem"
fi
